/Engine/Plugins/FX/Niagara/Source/NiagaraEditor/Public/NiagaraParameterMapHistory.h
Important. Must be called for each routing of the parameter map. This feeds the list used by TraceParameterMapOutputPin.
int32 RegisterParameterMapPin ( int32 WhichParameterMap, const [FPin](API\Plugins\NiagaraEditor\TNiagaraParameterMapHistoryBuild-\FPin) * Pin )